Vacuum pressure gauge

ABSTRACT

A vacuum pressure gauge is described herein. One apparatus includes an ion trap configured to trap antimatter therein in a vacuum chamber, and a controller configured to determine a lifetime of the antimatter trapped in the ion trap and determine a pressure in the vacuum chamber based, at least in part, on the determined lifetime of the antimatter.

PRIORITY INFORMATION

This application is a continuation of U.S. application Ser. No.14/699,409, filed Apr. 29, 2015, the entire specification of which isincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a vacuum pressure gauge.

BACKGROUND

There are many different types of pressure gauges that can be used todetermine (e.g., measure and/or calculate) the pressure in manydifferent types of environments. For example, a vacuum pressure gaugemay be used to determine the pressure in a vacuum chamber.

Previous vacuum pressure gauges, however, may only work within a certainpressure range. That is, if the pressure in the vacuum chamber isoutside of the range, the gauge may not be able to accurately determinethe pressure. For example, previous vacuum pressure gauges may only workdown to a pressure of about 10⁻¹² or 10⁻¹³ torr. That is, previouspressure gauges may not be able to accurately determine the pressure ina vacuum chamber if the pressure in the vacuum chamber is less than10⁻¹² or 10⁻¹³ torr.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a vacuum pressure gauge in accordance with one ormore embodiments of the present disclosure.

FIG. 2 illustrates a cross-sectional view of a portion of a vacuumpressure gauge in accordance with one or more embodiments of the presentdisclosure.

FIG. 3 illustrates a flow chart of a method of determining pressure in avacuum chamber in accordance with one or more embodiments of the presentdisclosure.

DETAILED DESCRIPTION

A vacuum pressure gauge is described herein. For example, one or moreembodiments include an ion trap configured to trap antimatter therein ina vacuum chamber, and a controller configured to determine a lifetime ofthe antimatter trapped in the ion trap and determine a pressure in thevacuum chamber based, at least in part, on the determined lifetime ofthe antimatter.

A vacuum pressure gauge in accordance with the present disclosure canhave (e.g., work within) a greater pressure range than previous vacuumpressure gauge. For example, a vacuum pressure gauge in accordance withthe present disclosure may be able to work at extremely low pressures(e.g., pressures less than 10⁻¹² or 10⁻¹³ torr). That is, a vacuumpressure gauge in accordance with the present disclosure may be able toaccurately determine the pressure in a vacuum chamber if the pressure inthe vacuum chamber is extremely low (e.g., less than 10⁻¹² or 10⁻¹³torr).

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof. The drawings show by wayof illustration how one or more embodiments of the disclosure may bepracticed.

These embodiments are described in sufficient detail to enable those ofordinary skill in the art to practice one or more embodiments of thisdisclosure. It is to be understood that other embodiments may beutilized and that mechanical, electrical, and/or process changes may bemade without departing from the scope of the present disclosure.

As will be appreciated, elements shown in the various embodiments hereincan be added, exchanged, combined, and/or eliminated so as to provide anumber of additional embodiments of the present disclosure. Theproportion and the relative scale of the elements provided in thefigures are intended to illustrate the embodiments of the presentdisclosure, and should not be taken in a limiting sense.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 102 may referenceelement “02” in FIG. 1, and a similar element may be references as 202in FIG. 2.

As used herein, “a” or “a number of” something can refer to one or moresuch things. For example, “a number of ions” can refer to one or moreions. Additionally, the designator “N” as used herein, particularly withrespect to reference numerals in the drawings, indicates that a numberof the particular feature so designated can be included with a number ofembodiments of the present disclosure.

FIG. 1 illustrates a vacuum pressure gauge 100 in accordance with one ormore embodiments of the present disclosure. Vacuum pressure gauge 100can be used to determine (e.g., measure and/or calculate) the pressurein a vacuum chamber, such as vacuum chamber 104 illustrated in FIG. 1.

As shown in FIG. 1, vacuum pressure gauge 100 can include an ion trap102, which can be inserted into and sealed (e.g. hermetically sealed) invacuum chamber 104. While in vacuum chamber 104, ion trap 102 can trapantimatter (e.g., antimatter ions) therein. For example, ion trap 102can trap a number of positrons therein.

Ion trap 102 can be, for example, a Penning trap (e.g., an open endcapPenning trap). Ion trap 102, and the process of trapping antimattertherein, will be further described herein (e.g., in connection with FIG.2).

As shown in FIG. 1, vacuum pressure gauge 100 can include a controller106 outside of vacuum chamber 104 and coupled to ion trap 102.Controller 106 can be, for example, an electronic controller that iselectronically connected to ion trap 102 via a number of wires, as willbe further described herein (e.g., in connection with FIG. 2).

Although not shown in FIG. 1 for simplicity and so as not to obscureembodiments of the present disclosure, controller 106 can include amemory and a processor. The memory can be any type of storage mediumthat can be accessed by the processor to perform various examples of thepresent disclosure. For example, the memory can be a non-transitorycomputer readable medium having computer readable instructions (e.g.,computer program instructions) stored thereon that are executable by theprocessor to determine the pressure in vacuum chamber 104 in accordancewith the present disclosure. That is, the processor can execute theexecutable instructions stored in the memory to determine, the pressurein vacuum chamber 104 in accordance with the present disclosure.

The memory can be volatile or nonvolatile memory. The memory can also beremovable (e.g., portable) memory, or non-removable (e.g., internal)memory. For example, the memory can be random access memory (RAM) (e.g.,dynamic random access memory (DRAM) and/or phase change random accessmemory (PCRAM)), read-only memory (ROM) (e.g., electrically erasableprogrammable read-only memory (EEPROM) and/or compact-disk read-onlymemory (CD-ROM)), flash memory, a laser disk, a digital versatile disk(DVD) or other optical disk storage, and/or a magnetic medium such asmagnetic cassettes, tapes, or disks, among other types of memory.

As an example, controller 106 can determine (e.g., measure) the lifetimeof the antimatter trapped in ion trap 102, and determine (e.g.,calculate) the pressure in vacuum chamber 104 based, at least in part,on the determined lifetime of the trapped antimatter. That is, thepressure in vacuum chamber 104 can be related to, and thereforedetermined based on, the lifetime of the antimatter trapped in ion trap102. For instance, there may be a linear relationship between thelifetime of the antimatter trapped in ion trap 102 and the pressure invacuum chamber 104. Because the lifetime of the trapped antimatter maybe relatively long at extremely low pressures, (e.g., pressures lessthan 10⁻¹² or 10⁻¹³ torr), the lifetime may be an accurate indicator ofthe pressure in vacuum chamber 104 at extremely low pressures.

For instance, controller 106 can determine the quantity (e.g., amount)of particles in the vacuum chamber based, at least in part, on thedetermined lifetime of the trapped antimatter, and then determine thepressure in vacuum chamber 104 based, at least in part, on thedetermined quantity of particles. That is, the pressure in vacuumchamber 104 can be related to (e.g., directly proportional to) thequantity of particles in the vacuum chamber, and the quantity ofparticles in the vacuum chamber can be determined based on the lifetimeof the trapped antimatter.

The lifetime of the antimatter trapped in ion trap 102 can correspond tothe annihilation rate of the antimatter trapped in the ion trap. Thatis, the lifetime of the antimatter trapped in ion trap 102 cancorrespond to the amount of time before the trapped antimatter isannihilated by the particles in vacuum chamber 104 (e.g., the amount oftime the antimatter remains trapped in ion trap 102 before the particlesin vacuum chamber 104 collide with the trapped antimatter). As theparticles in vacuum chamber 104 collide with the antimatter trapped inion trap 102, the antimatter will annihilate and reduce the quantity ofantimatter ions trapped in ion trap 102. Hence, the lifetime of theantimatter trapped in ion trap 102 can be inversely proportional to thequantity of particles in vacuum chamber 104 (e.g., the more particles inthe chamber, the shorter the lifetime of the trapped antimatter).

Controller 106 can determine the annihilation rate of the antimattertrapped in ion trap 102, and therefore the lifetime of the trappedantimatter, by measuring the quantity of antimatter ions trapped in thetrap versus time. For example, controller 106 can determine theannihilation rate of the antimatter trapped in ion trap 102 bydetermining (e.g., measuring and/or counting) the quantity of antimatterions trapped in the trap at an initial time, and determining (e.g.,measuring and/or counting) the quantity of antimatter ions trapped inthe trap at a subsequent time. The difference between the two quantitiescan correspond to the amount of antimatter ions that have beenannihilated in that time, which can be used to determine theannihilation rate.

Controller 106 can determine (e.g., measure) the quantity of antimatterions trapped in ion trap 102 by amplifying the electronic signal inducedin the trap (e.g., in the electrodes in the trap, as described inconnection with FIG. 2) by the trapped antimatter, and determining(e.g., measuring) the frequency bandwidth (e.g., the width in frequencyspace) of the amplified electronic signal, which may be proportional tothe quantity of antimatter ions trapped in the trap, as will beunderstood by those of skill in the art. Hence, controller 106 candetermine (e.g., calculate) the annihilation rate, and therefore thelifetime, of the antimatter trapped in ion trap 102, based on (e.g., bymeasuring and/or monitoring) the frequency bandwidth of the amplifiedsignal. Controller 106 can amplify the electronic signal induced in trapby the trapped antimatter using an amplifier.

FIG. 2 illustrates a cross-sectional view of a portion of a vacuumpressure gauge 200 in accordance with one or more embodiments of thepresent disclosure. Vacuum pressure gauge 200 can be, for example,vacuum pressure gauge 100 previously described in connection with FIG.1, and the portion of the vacuum pressure gauge illustrated in FIG. 2can be the portion of the gauge in vacuum chamber 104 illustrated inFIG. 1.

As shown in FIG. 2, vacuum pressure gauge 200 can include an ion trap202. Ion trap 202 can be, for example, ion trap 102 previously describedin connection with FIG. 1. For instance, ion trap 202 can be a Penningtrap (e.g., an open endcap Penning trap) that can trap antimatter (e.g.,antimatter ions) therein. In the example illustrated in FIG. 2, a singleantimatter ion 210 is trapped in ion trap 202. However, embodiments ofthe present disclosure are not so limited; ion trap 202 can trap anynumber of antimatter ions therein. For example, ion 210 illustrated inFIG. 2 could represent a plurality (e.g., a cloud) of antimatter ions.

As shown in FIG. 2, ion trap 202 can include a number of electrodes(e.g., ring electrodes, end cap electrodes, compensation electrodes,etc.) 216-1, 216-2, . . . 216-N. Each electrode 216-1, 216-2, . . .216-N can be separated by a different portion of an insulating spacer220 (e.g., a first portion of insulating spacer 220 can be betweenelectrode 216-1 and electrode 216-2, a second portion of insulatingspacer 220 can be between electrode 216-2 and the next electrode, etc.),as illustrated in FIG. 2.

Electrodes 216-1, 216-2, . . . 216-N can form an accumulation region ofion trap 202 in which the antimatter (e.g., antimatter ion 210) can betrapped, as illustrated in FIG. 2. For example, one of electrodes 216-1,216-2, . . . 216-N can be a permanent magnet that can provide a magneticfield which forms the magnetic field component of the Penning trap.

As shown in FIG. 2, each electrode 216-1, 216-2, . . . 216-N can becoupled to a different signal wire 222-1, 222-2, . . . 222-N (e.g.,electrode 216-1 can be coupled to signal wire 222-1, electrode 216-2 canbe coupled to signal wire 222-2, etc.). Each signal wire 222-1, 222-2, .. . 222-N can be coupled to a controller located outside of the vacuumchamber (e.g., controller 106 previously described in connection withFIG. 1) via electronics feedthrough 224. For instance, each signal wire222-1, 222-2, . . . 222-N can be bundled by, and enter and exit thevacuum chamber through, electronics feedthrough 224. The controller canapply voltages to electrodes 216-1, 216-2, . . . 216-N via signal wires222-1, 222-2, . . . 222-N to load and trap antimatter in ion trap 202.

As shown in FIG. 2, vacuum pressure gauge 200 can include a positronsource 212 and a tungsten moderator 214. Positron source 212 can be, forexample, a radioactive positron source, such as a sodium-22 positronsource. Tungsten moderator 214 can be, for example, a single crystaltungsten moderator.

Positron source 212 can load antimatter (e.g., positrons) into ion trap202 through tungsten moderator 214. For example, during the loading,positrons from positron source 212 can pass through moderator 214, formpositronium, and become ionized in ion trap 202.

Upon the antimatter being loaded into ion trap 202, the antimatter canbe trapped in the ion trap. For example, during the trapping, thecontroller can prevent (e.g., block) positron source 212 from loadingadditional antimatter into ion trap 202 by biasing tungsten moderator214 with a large potential voltage, while applying a potential voltageto electrodes 216-1, 216-2, . . . 216-N to trap the loaded antimatter inion trap 202. Once the antimatter has been trapped in ion trap 202, thecontroller can begin the process to determine the lifetime of theantimatter and the pressure in the vacuum chamber, as previouslydescribed herein (e.g., in connection with FIG. 1).

As shown in FIG. 2, vacuum pressure gauge 200 can include a vacuumflange 226 connected to ion trap 202 (e.g., through an insulating spacer220) and positron source 212. Vacuum flange 226 can be inserted into thevacuum chamber in order to insert and seal (e.g., hermetically seal) iontrap 202 in the vacuum chamber. Further, electronics feedthrough 224 canbe included within vacuum flange 226 such that wires 222-1, 222-2, . . .222-N can enter and exit the vacuum chamber, as illustrated in FIG. 2.

FIG. 3 illustrates a flow chart of a method 330 of determining pressurein a vacuum chamber in accordance with one or more embodiments of thepresent disclosure. The vacuum chamber can be, for example, vacuumchamber 104 previously described in connection with FIG. 1. Method 330can be performed by, for example, vacuum pressure gauge 100 and 200previously described in connection with FIGS. 1 and 2, respectively.

At block 332, method 330 includes loading antimatter (e.g., positrons)into an ion trap in the vacuum chamber. The ion trap can be, forexample, ion trap 102 and 202 previously described in connection withFIGS. 1 and 2, respectively. The antimatter can be loaded into the iontrap from a positron source and through a tungsten moderator, aspreviously described herein (e.g., in connection with FIG. 2).

At block 334, method 330 includes trapping the antimatter in the iontrap. The antimatter can be trapped in the ion trap by, for example,biasing the tungsten moderator with a large potential voltage whileapplying a potential voltage to the electrodes of the ion trap, aspreviously described herein (e.g., in connection with FIG. 2).

At block 336, method 330 includes determining the lifetime of theantimatter trapped in the ion trap. The lifetime of the trappedantimatter can be determined by, for example, controller 106 previouslydescribed in connection with FIG. 1. The lifetime of the trappedantimatter can correspond to the annihilation rate of the trappedantimatter, as previously described herein (e.g., in connection withFIG. 1).

At block 338, method 330 includes determining the pressure in the vacuumchamber based, at least in part, on the determined lifetime of theantimatter. The pressure can be determined by, for example, controller106, and can be related to the quantity of particles in the vacuumchamber, as previously described herein (e.g., in connection with FIG.1).

At block 340, method 330 includes removing (e.g., dumping) any remainingantimatter from the ion trap upon determining the pressure in the vacuumchamber. The remaining antimatter may be, for example, any antimatterthat may not have been annihilated during the process of determining thepressure in the vacuum chamber. Upon removing the remaining antimatterfrom the ion trap, method 330 can be repeated (e.g., return to block332).

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anyarrangement calculated to achieve the same techniques can be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments of thedisclosure.

It is to be understood that the above description has been made in anillustrative fashion, and not a restrictive one. Combination of theabove embodiments, and other embodiments not specifically describedherein will be apparent to those of skill in the art upon reviewing theabove description.

The scope of the various embodiments of the disclosure includes anyother applications in which the above structures and methods are used.Therefore, the scope of various embodiments of the disclosure should bedetermined with reference to the appended claims, along with the fullrange of equivalents to which such claims are entitled.

In the foregoing Detailed Description, various features are groupedtogether in example embodiments illustrated in the figures for thepurpose of streamlining the disclosure. This method of disclosure is notto be interpreted as reflecting an intention that the embodiments of thedisclosure require more features than are expressly recited in eachclaim.

Rather, as the following claims reflect, inventive subject matter liesin less than all features of a single disclosed embodiment. Thus, thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separate embodiment.

What is claimed:
 1. A vacuum pressure gauge, comprising: a controllerconfigured to: determine a lifetime of antimatter trapped in a vacuumchamber; and determine a pressure in the vacuum chamber based, at leastin part, on the determined lifetime of the antimatter.
 2. The vacuumpressure gauge of claim 1, wherein the antimatter is trapped in an iontrap in the vacuum chamber.
 3. The vacuum pressure gauge of claim 2,wherein the controller is electronically connected to the ion trap via anumber of wires
 4. The vacuum pressure gauge of claim 1, wherein: thevacuum pressure gauge includes an amplifier configured to amplify anelectronic signal induced by the antimatter trapped in the vacuumchamber; and the controller is configured to determine the lifetime ofthe antimatter based, at least in part, on the amplified electronicsignal.
 5. The vacuum pressure gauge of claim 4, wherein the controlleris configured to determine the lifetime of the antimatter based, atleast in part, on a frequency bandwidth of the amplified electronicsignal.
 6. The vacuum pressure gauge of claim 1, wherein: the vacuumpressure gauge includes a positron source and a tungsten moderator; andthe positron source is configured to load the antimatter into the vacuumchamber through the tungsten moderator.
 7. The vacuum pressure gauge ofclaim 1, wherein the vacuum pressure gauge includes a vacuum flangeconfigured to seal the vacuum chamber.
 8. The vacuum pressure gauge ofclaim 1, wherein the controller includes: a memory; and a processorconfigured to execute instructions stored in the memory to determine thelifetime of the antimatter and determine the pressure in the vacuumchamber.
 9. A method of determining pressure in a vacuum chamber,comprising: determining, by a controller, an annihilation rate ofantimatter trapped in a vacuum chamber; and determining, by thecontroller, a pressure in the vacuum chamber based, at least in part, onthe determined annihilation rate of the antimatter.
 10. The method ofclaim 9, wherein the method includes: determining a lifetime of theantimatter based on the determined annihilation rate of the antimatter;and determining the pressure in the vacuum chamber based, at least inpart, on the determined lifetime of the antimatter.
 11. The method ofclaim 9, wherein the method includes determining the annihilation rateof the antimatter by determining a quantity of antimatter ions trappedin the vacuum chamber at two different times.
 12. The method of claim 9,wherein the determined pressure is less than 10⁻¹² torr.
 13. The methodof claim 9, wherein the method includes preventing additional antimatterfrom being loaded into the vacuum chamber while the antimatter istrapped in the vacuum chamber and the annihilation rate of theantimatter is being determined.
 14. A vacuum pressure gauge, comprising:a controller configured to: determine a lifetime of antimatter trappedin a vacuum chamber; determine a quantity of particles in the vacuumchamber based, at least in part, on the determined lifetime of theantimatter; and determine a pressure in the vacuum chamber based, atleast in part, on the determined quantity of particles.
 15. The vacuumpressure gauge of claim 14, wherein the controller is configured todetermine the lifetime of the antimatter trapped in the vacuum chamberbased on an amount of time before the antimatter trapped in the vacuumchamber is annihilated by particles in the vacuum chamber.
 16. Thevacuum pressure gauge of claim 14, wherein the vacuum pressure gaugeincludes a number of electrodes configured to form an accumulationregion in the vacuum chamber in which the antimatter is trapped.
 17. Thevacuum pressure gauge of claim 16, wherein: the vacuum pressure gaugeincludes an insulating spacer; and each respective electrode isseparated by a different portion of the insulating spacer.
 18. Thevacuum pressure gauge of claim 16, wherein: the vacuum pressure gaugeincludes a number of signal wires coupled to the controller; and eachrespective electrode is coupled to a different one of the number ofsignal wires.
 19. The vacuum pressure gauge of claim 18, wherein thevacuum pressure gauge includes an electronic feedthrough configured tobundle the number of signal wires.
 20. The vacuum pressure gauge ofclaim 14, wherein the controller is outside of the vacuum chamber.